ANKARA (Reuters) - Energy ties and the fate of Crimean Tatars will top the agenda when Turkish President Tayyip Erdogan meets his Ukrainian counterpart in Kiev on Friday, but concrete deals are unlikely as he seeks to avoid straining relations with Moscow.

Turks have close kinship bonds with the Muslim, Turkic-speaking Tatar minority in Crimea, the Black Sea peninsula Moscow annexed from Ukraine a year ago. Erdogan has repeatedly warned that the instability could have regional repercussions.

"Our brothers, who in the past suffered mass deportations, were able to return to their homelands after many years. Unfortunately they ... have been seriously impacted by (recent) developments there," Erdogan told reporters.

"Turkey is closely following the situation of our brothers," he said before leaving for his meeting with Ukrainian President Petro Poroshenko, describing pressure on Tatar community leaders as "unacceptable".

But Turkey also has deepening trade ties with Russia and has been reluctant to openly criticize Moscow. Erdogan spoke by phone with Russian President Vladimir Putin this week, discussing energy deals and the Ukraine crisis.

Russian gas exporter Gazprom said in January it planned to build an undersea gas pipeline via the Turkish-Greek border -- a project informally known as "Turkish Stream" -- as it seeks to supply Europe while by-passing Ukraine.

Ukrainian officials are likely to be looking for assurances from Erdogan and Energy Minister Taner Yildiz during their trip that those ties will not harm Ukrainian interests.

"One of the most important topics during Erdogan’s visit will be energy," a senior Turkish official said, noting that Ukraine still wants to build a liquefied natural gas (LNG) plant on the Black Sea coast, a project Ankara opposes.